Monitoring of intracranial pressure (“ICP”) for instantaneous pressure as well as for changes in pressure—especially among patients with head injury, stroke edema, or acute intracranial hemorrhage—provides important information on which to base medical and surgical treatment. Elevations in intracanial pressure may inhibit the supply of blood to the brain, causing tissue damage and possible fatality if left untreated.
The rapid detection of elevated intracranial pressure (EICP) in patients with head trauma and spontaneous intracranial hemorrhage is critical for physicians and first responders to develop the best therapy to reduce death and disability. In the field where CT scanning is unavailable, or where many patients require rapid triage (e.g., combat theater, disaster scenes, multi-casualty occurrences), a noninvasive method that could be performed quickly and does not require the experienced judgment of an image would be useful to determine whether a patient's ICP is elevated or changing.
Existing ICP monitoring devices require a neurosurgeon to drill a hole in the patient's skull for the insertion of an intracranial catheter through which one measures ICP. The types of invasive devices currently in use include intraventricular catheters, fiber optic monitors, subarachnoid bolts, and epidural monitors. Despite the risk of hemorrhage, malfunction, herniation, infection, and the expensive cost, the use of intracranial catheters remains standard method for diagnosing intracranial hypertension.
An alternative option for measurement of ICP is to puncture the lumbar dura (i.e., perform a spinal tap) to measure cerebrospinal fluid (“CSF”) pressure. CSF pressure can serve as a proxy for ICP.
Because of the risks inherent in these invasive procedures, other methods have been developed to address conditions where intracranial catheters are not feasible. Some noninvasive techniques include computed tomography (“CT”) scan of the head, ophthalmoscopy, and transcranial Doppler (“TCD”) sonography. Each of these techniques, however, has drawbacks.
A CT scan of the head is time consuming and requires transfer of critically ill patients and supporting devices to specialized facilities. Ophthalmoscopy necessitates experienced examiners. TCD also requires well trained observers.
Accordingly, there is a need in the art for noninvasive methods of accurately assessing ICP over a range of pressures and for related devices for performing such methods.